Very little of the filming took place in the actual mansion. The mansion's design in reality is extremely cramped, making filming very difficult. As such, most of the mansion's interior needed to be recreated on sound stages.
Lionsgate bought the film and photography rights to the Winchester Mansion for this film. So now tourists aren't allowed to take any pictures of the interior of the mansion, because a tourist photo would be in direct competition with a Hollywood movie.
Sarah Winchester constantly built, and rebuilt the house for 38 years, believing if she stopped, the spirits of those killed by Winchester rifles would kill her. The Winchester house has windows and doors in the floor, doors that open into walls or nothing, and stairs to nothing or into the ceiling. She was obsessed with the number 13.
The promotional image for the film of Helen Mirren sitting in the carriage in mourning clothes mirrors the only known photograph of the reclusive Sarah Winchester on the estate, which is seen on the tour of the mansion in San Jose.
"Ghost Dance", the 45th and last issue from Saga of the Swamp Thing (February 1986), written by Alan Moore, was inspired, like this film, by the Sarah Winchester's story about the house haunted by the ghosts of all the people who were slaughtered by her family's guns.
Sarah Winchester had severe, debilitating arthritis and had a series of short risers, only 3 or 4 inches high, in place of stairs as it was very painful for her to raise her foot more than a few inches.
World-Renowned Parapsychologist/Paranormal Investigator Christopher Chacon conducted the only scientific investigation of the reported haunt phenomena of the Winchester mansion and property in the early 1990's which was sanctioned by the Winchester property owners.